1. Field of the Invention
This present invention relates to orifice test calibration devices for testing the functionality of a protective mask tester.
2. Brief Description of the Related Art
Protective respiratory masks protect the wearer's face, eyes, and lungs from the effects of hazardous airborne chemical or biological agents under circumstances such as soldiers operating in a chemically or biologically contaminated environment. Protective masks may additionally be used in numerous other operating environments, such as firefighting, environmental cleanup, manufacturing, medical hazard handling, quarantining of patients with highly contagious pathogens, biological and chemical warfare, mining, paint applications, construction, and other applications where persons may come into contact with hazardous substances especially airborne hazards. Typically, the protective mask is worn over the wearer's face and seals the face from the ambient atmosphere. The protective mask cleans the air entering the mask by means of a filter device generally having chemically impregnated fibers, HEPA filters, and a bed of adsorbent material such as activated charcoal. During operation, a one-way inlet valve in the mask allows air drawn in by the wearer's lungs to pass through a filter containing the filtration media to provide a flow of filtered air into the mask. As the wearer exhales, the exhaled gas is expelled through a one-way outlet valve out of the mask and the process is repeated with each breath.
The protective mask provides the wearer with protection from toxic airborne substances only with proper fit and function. Therefore, it is extremely important that the mask be properly tested to ensure that it will protect the wearer from these life threatening agents. Proper testing of the protective masks requires that the protective mask testers be properly calibrated. Gas mask testers, such as the Army's M14, commercially available TDA-99M, TDA-99B, TDA-104, Q204 and the Joint Service Mask Leakage Tester (JSMLT), provide a platform for testing the serviceability of gas masks particularly with regard to leakage of the mask. These testers may be portable or fixed devices having clamping mechanisms, inflatable mask seals and clamping adapters for fixing the masks in place for testing. For example, the assessment process of a protective mask using the portable TDA-99M Respirator Function Tester uses a microprocessor to test the reliability of the functional components of the mask, testing for overall mask integrity, the drink train functions and outlet valve assembly operation. The TDA-99M is a self-contained unit with an inflatable mask seal, different sized headforms and several adapters that permit leak testing of protective masks. The assessment process begins with a visual inspection of each mask for numerous specified defects followed by a mechanical evaluation using the TDA-99M. During the mechanical testing process, the mask is strapped on the tester's headform and covered with a shroud. The mask seal is then inflated, sealing the mask to mimic a proper fit. Inflatable seals generally include a conventional solenoid fill port through which pressurized air is directed to inflate the seal. Once the seal is inflated, a fine, non-toxic aerosol is dispersed inside the shroud and on the outside of the protective mask. The TDA-99M creates a pressure differential between the interior and exterior of the protective mask, i.e., it attempts to draw the aerosol through the protective mask, using a vacuum within the protective mask area while simultaneously sampling the air inside the protective mask. If the air inside the protective mask is unacceptable, an alarm sounds to indicate the protective mask is leaking. The protective mask, once passing the overall leakage test, is tested for problems associated with the drink train and outlet valve assembly. However, the protective mask testers only provide adequate validation of the protective masks when the protective mask testers are properly calibrated. Generally, these systems do not have external testing devices to verify the tester devices are working properly.
There is a need in the art for mechanisms to provide reliable and efficient calibration of protective mask testers. The present invention addresses these and other needs.